The spat between Virginia and federal regulators over Chesapeake Bay restoration is again flaring up, this time with leaders in Richmond complaining about inconsistencies found in a new computer model.

That Gov. Bob McDonnell’s administration would object to the model isn’t surprising; officials have, after all, criticized it since the U.S. Environmental Protection Agency began its latest effort to remove the bay from a national dirty waters list.

What’s interesting is their gripe that localities, such as James City County, have transformed — seemingly overnight — from polluters to ideal land stewards.

For example, under the previous model, county landowners were supposed to cut the amount of pollutants discharged into the bay and its tributaries by 8 to 20 percent. According to the latest model, landowners do not have to reduce pollution at all.

In fact, they could add loads of phosphorus and sediment and still have a cushion that would keep them from having to install stream buffers, rain barrels and other pollution reduction devices.

Virginia Secretary of Natural Resources Doug Domenech said while the James City County case is an extreme example, it nonetheless illustrates problems with the EPA model. Localities can’t adequately prepare to cut pollution when the target is moving, he said.

EPA officials have consistently said the model is not perfect and that it will evolve as the 15-year cleanup does. They say the broad goal of limiting bay pollution — and consequently reducing the size of oxygen-starved dead zones in the bay — remains the same.

The row comes after months of relative calm between the two sides.

Remember, Domenech complained loudly last year around this time as the due date for the state’s pollution reduction plan neared. The EPA and Virginia eventually reached a deal that some say eased the burden on the state.

Another deadline looms. Virginia is required to submit a more detailed plan to the EPA by Dec. 15.